Swedish police have arrived in Thailand to investigate reports that a 12-year-old survivor of the tsunami has been kidnapped from a hospital.

Two officers are helping Kristian Walker's family and Thai police search for him, amid fears he may have been taken by child sex traffickers.

Kristian was reportedly injured when the giant waves hit Khao Lak.

Local doctors identified the boy from photographs, saying a European man with a moustache had accompanied him.

Kristian's American father, Dan Walker from Stockholm, was quoted as saying: "At first I thought my son was dead but then my father went to a hospital in Thailand with his picture and everyone at the hospital reacted because they recognised him".

"He was seen twice at the hospital - on the same day as the tsunami and the day afterwards."

Dan Walker with his surviving children - his wife is missing presumed dead

Kristian Walker was on holiday
with his mother Madeleine Walker, 45, his 14-year-old brother and seven-year-old sister.

With Mrs Walker missing and feared dead, the boy's father dashed to Thailand from Stockholm, and discovered the brother and sister in a Phuket hospital.

The family fears that Kristian may have been taken out of Thailand in the chaos that followed the tsunami, when many Europeans were able to fly out without their passports.

Up to 7,000 Europeans are still missing, more than a week after the tsunami disaster.

More than a dozen planes have brought injured Scandinavians back home from Thailand.

Swedish Prime Minister Goran Persson has said more than 1,000 Swedes may have died in the catastrophe.